1. Field of the Invention
This invention relates to a multilaser device suitably used in an electrophotographic apparatus and emitting a plurality of laser beams.
2. Description of Related Art
A multibeam laser has heretofore been of a monolithic construction provided with a plurality of light emitting portions on a laser diode chip. In an image forming apparatus of an electrophotographic type, a plurality of beams are caused to scan by the use of this multibeam laser, and are applied onto a photosensitive drum to thereby effect latent image forming.
In the above-described monolithic type, however, an electric current is supplied to one of the plurality of light emitting portions on the laser diode chip, whereby from the heat generation thereof, the threshold value electric currents of the other light emitting portions are increased and further, this leads to a reduction in the quantity of emitted light. This phenomenon is particularly remarkable in an increase in a driving current resulting from the heightening of a light output. In the image forming apparatus, such a reduction in the quantity of emitted light results in the uneven density of an image and deteriorates the quality of printing.
As one of methods of solving the above-noted problem, there is a method of carrying a plurality of laser diode chips to thereby form a multibeam, but this method gives rise to the problem that depending on the mounting accuracy of the laser diode chips in a semiconductor laser, the distance from a light emitting point to a photosensitive drum differs among the laser diode chips, whereby the converging property of a spot becomes uneven.